1. Field of the Invention
The present invention relates to an automatic locking and releasing arrangement for vehicular seat belt whereby a seat belt is automatically locked when an occupant of an automobile or the like sits on a seat and the belt is automatically released when the occupant gets off the automobile.
2. Description of the Prior Art
Various types of seat belts for protecting occupants of automobiles and the like have been proposed. Also available are various types of devices for effecting automatic lock and release of a seat belt.
For example, a so-called three-point type seat belt system is shown in FIG. 9, in which a belt retractor 4 is disposed at a side portion of a seat 3 and an end portion of one belt 1a out of two belts to be wound up by the retractor 4 is attached to a door 6 of a vehicle to constitute a shoulder belt, while an end portion of the other belt 1b is attached to a slider and a waist belt is constituted by sliding of the slider along a guide rail 7 mounted on the inner surface of the door 6.
Another type of a seat belt system is shown in FIG. 10, in which a guide rail 11 is attached to a side panel of a vehicle body along the opening portion of the door 6, and a slider 5 which supports an end portion of a shoulder belt 1a is allowed to slide through the interior of the guide rail 11 to facilitate lock and release of the shoulder belt. For driving said slider there is provided a cable having a member adapted to engage the slider, which cable is operated by means of a drive unit such as a motor, thereby affording a motor-driven seat belt system.
Such motor-driven type seat belt system requires an anchor device for fixing the slider of a buckle in a seat belt locked position automatically and positively and for releasing the slider automatically.
Kazuo Yamamoto has disclosed this type of art in U.S. Pat. No. 4,467,070 already granted a patent right in the U.S.
According to this art, a connector and a cam are attached to a cable in predetermined positions so that the slider of a buckle slides while being sandwiched by the connector and the cam, and an anchor latch provided in an anchor portion and a pawl of the slider are engaged with and disengaged from each other by operating the anchor latch with the cam. In this connection, the prior art in question is constructed so that the connector and the cam can travel a predetermined distance with respect to the slider, thereby bringing the anchor latch into engagement or disengagement with the cam automatically.
On the other hand, in the construction of the guide rail 11, a bent portion 11a having a small radius of curvature is present, so it is necessary to provide means for reducing the sliding resistance when the connector and the cam pass through said bent portion. Particularly, where the cable is not an endless type but a winding type, there is fear of the occurrence of buckling due to the sliding resistance at such bent portion during delivery of the cable, which would make the sliding motion impossible.